Unless you had an independent eye witness that saw the ball cause the issue and had their testimony or the ball imbedded in the windshield, it'd be almost impossible to prove it was a ball on location that did the damage. Beyond that you'd need reasonable proof it came from a player legally playing the course to even get started along such a path. It would not be out of the range of possibility for someone to have damage and plant a golf ball then say it happened if it did not, similar situations happen all the time. FL is actually one of the leading states in staged car accidents if not the top one.
The golf ball in question was indeed found at the scene. Doing a little CSI of my own, taking into account the impact postion, direction and angle of attack the offending golf ball was indeed were it should have been.
Given the fact the 1 or more golf balls was found each day around the villa/parking area in question, I would be surprised if this has not occured in the past.
As a long time golfer I am fully aware that errant shots are a part of golf. On this hole in particular, if unfamiliar with the hole, based on the layout, one would have no idea there was a Treehouse or Cars in the path.
When it happened, early in our trip, I chalked it up as stuff happens. I didnt let it bother me or negatively impact our family vacation. I immediately thought that Disney was NOT going to cover this and it would be my responsibility out of pocket (deductible $500). I went to the front desk to report the incident, they called security, we filed a report and they gave me a claims number to call. So I then thought, well, maybe Disney will take care of this. From the OP, they are not.
From Disney's standpoint I think it could have been handled better as follows:
1) While I am aware of the potential "Danger" from an errant golf ball, someone that is not a golfer that gets assigned that villa(7035) might not be. There is a chance of getting hit while sitting on the deck or even when walking from villa to car. I think that should be communicated in some way. I am not complaining, I am simply saying. I requested this villa for its location and it worked out great from that standpoint.
2) Had I been told that , No sorry, disney does not cover that type of damage, I may have had the windshield fixed before returning the rental car, just so I would not have to go through the hassle, although I must say Alamo was great when I returned the car and it was a quick process to get me out of there. Total cost from Alamo, $201.14 for the repair and $50 Administrative fee, $251.14 which I'll pay and chalk up as a cost of the vacation.
We had a great vacation and loved the THV and will recommend to anyone that asks.